The biosynthesis of blood group substances is known. The isoantigenicity of such substances is determined by the terminal sugar of the oligosaccharide chain of the glycoprotein or glycolipid. The absence of A,B,H isoantigens in carcinomatous and some premalignant lesions of the gastrointestinal tract has been demonstrated by this investigator using the mixed cell agglutination reaction. This has been interpreted as representing incomplete biosynthesis of blood group substances by malignant cells. This research proposal will determine using both the mixed cell agglutination reaction and immunofluorescent means the antigenic components of blood group substances which are retained by malignant cells which have lost A,B, H isoantigenicity. It is expected that "precursor substance" which has immunological cross reactivity with Type XIV pneumococcus capsular polysaccharide will be detected in such tissues. The topographical relationship of other "tumor specific" antigens such as the carcinoembryonic antigens to those of "precursor substance" antigens in malignant tissues will be studied.